Various forms of electrophotographic copying machines are known in the prior art. Some of these machines are intended for that part of the copier market in which the price at which the machine can be sold is limited. One type of copier intended for this portion of the market employs a reciprocable platen which carries the original past stationary optics. Most of these copiers are intended for use with a supply of copy paper of only one size. Where a copy of a longer original is to be made, the supply of copy material must be replaced with copy material corresponding in size to the longer sized original. Copiers of the type employing a reciprocating platen are not adapted to copy the pages of, for example, a relatively heavy book. Neither do they accommodate semi-automatic or automatic document feeders.
Copying machines of the type just described, also are generally used as "convenience" copiers in that in most instances only a single copy at a time is being made It has been found that at a location for which such a convenience copier is useful, the average number of copies made for each use of the machine, is about 1.3 copies. It will readily be appreciated that a short first copy time is an extremely important consideration for a copier which will be used as a convenience copier.
Further desiderata, not only for copiers of the type discussed hereinabove, but for all copiers, include accessibility of all points on the paper path without removal of machine parts, so as to permit paper jams to be cleared by operating personnel to reduce the frequency of service calls. Parts or subassemblies of the machine should be readily removable and replaceable for ease of servicing. It is further desirable that the pick-off element of the machine not be in continuous engagement with the surface of the drum.
In all of the copying machines of the prior art of which applicant is aware, the copy is delivered to the output tray or the like of the machine by pushing or propelling the copy out of the machine toward the delivery tray. Such an operation results in an output stack made up of sheets the leading edges of which are not precisely aligned. If a further operation of, for example, stapling the stack of output copies, is to be performed, some auxiliary means must be provided for precisely aligning the leading edges of the sheets making up the output stack.